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| Home > Publications database > Analyse des phasensprungartigen Einsetzens der Passage humaner Erythrozyten durch Mikropipetten bei kritischen Temperaturen |
| Dissertation / PhD Thesis/Book | PreJuSER-34459 |
1999
Forschungszentrum, Zentralbibliothek
Jülich
Please use a persistent id in citations: http://hdl.handle.net/2128/3599
Report No.: Juel-3667
Abstract: The present work deals with the analysis of the temperature dependence of the deformational as well as passage behavior of human erythrocytes in micropipettes. The pipettes used had a typical inner diameter of about one third of those of the smallest capillaries in the human circulatory system. The aspiration pressure used was of physiologically relevant magnitude. A sudden transition from blockage to passage appeared for intact cells at To = 36,4±O,3°C. The transition of intact erythrocytes was interpreted as a gel-to-fluid phase transition of the highly concentrated intracellular hemoglobin solution. An enhanced intracellular calcium concentration hindered the cell passage. At an 1.7 fold enhanced aspiration force the transition occurred again at 36,4°±O,3°C. Low shear viscometry of pure, highly concentrated hemoglobin solutions in-between 20°C and 40°C also showed an sudden viscosity drop between 35°C and 37°C. A sudden temperature transition appeared as well when the intracellular calcium content was increased. The sudden onset of cell passages at To was most likely due to a breakdown of intermolecular hemoglobin bonds. Two distinct models have been elaborated to explain the effects of calcium and temperature on the viscosity of hemoglobin solutions. Hemoglobin depleted red blood cell ghosts (resealed ghosts) showed a phase transition like passage behavior as well, yet at a distinctly different transition temperature of Tg = 28,3±2,3°C. The ghost transition was explained as a so-called inverse temperature transition of the spectrin network tightly bound to the erythrocyte's inner membrane site. An inverse temperature transition is a sudden decrease of the spectrin lattice network's entropy at Tg with increasing temperature
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